I don't understand what all the fuss below is about. Some people must be upset with Mr. Robertson for reasons other than the actual content of the book. Yes, he does spell 'Os Luciados' a couple of different ways in this book, and that does seem to be poor editing; however, google indicates that the "misspellings" are all legitimate. I suppose a catholic might find fault with his characterization of Fatima as a "spiritual disneyland." But then, if he wrote about it from a Catholic perspective, it would be a theology rather than a history book.
This book is very obviously meant to be a quick overview of Portugese history for people who are on vacation there. My book dealer even helpfully put it in the "travel" section, rather than the history section. Many times in my travels, I found myself in an interesting place, completely at the mercy of the cretinous author of whatever travel book I was able to procure for myself. Having a slim book like this I can read while travelling, and refer to while in museums and other places of culture (say, to remind myself who Luis de Camoes might be) makes the trip that much more exciting and relevant. While travelling, you do not want some vast tome, impossible to carry around with you: you want a light reference, which includes timelines, and, yes, lists of Visigothic kings. I think this book admirably succeeds in its purpose for Portugal. My trip was dramatically enriched by having this book along. I probably wouldn't choose this book in studying for a test on Portugese history, and I did find it a bit dry in places and perhaps a bit spare in others. I also allow there may be better examples of this 'travel genre' on the subject of Portugese history, but those weren't available in the bookstore. I think the average english speaking tourist to Portugal will be just as pleased with this book as I was.